1. Field of the Invention
The present invention relates to a telephone equipment. More particularly, the invention pertains to a signaling device for determining whether a telephone line is in an on-hook or off-hook condition.
2. Description of the Prior Art
It is common in both business and residential settings to connect more than one telephone or device to a common telephone line. The indication of the shared telephone line being in an in-use or available state has traditionally been accomplished by repeatedly picking up the telephone and listening for a dial tone to indicate that the line was available. This type of arrangement is both tedious for the user waiting for the line to become available and creates annoyance to the user currently utilizing the line.
Various prior art devices and circuits are known in the art for detection of on-hook and off-hook conditions of a telephone line. However, these devices suffer in a number of regards. For example, many of such devices utilize complex or costly circuitry that is often directed for use with large telephone or switching systems. While others, require batteries or external power to operate, and rely on visual indicators to indicate line status which leads to both increased maintenance or installation and the repeated checking of the visual indicators by a user.
A more desirable device is one which would be simple and inexpensive and provide an improved manner of signaling that would not require repeated checking by a user. An additional desirable feature is one which would not require batteries or external power, but at the same would comply with the direct current requirements of the Federal Communications Commission.
As will be described in greater detail hereinafter, the device and circuit of the present invention differs from those previously proposed and employs a number of novel features that render it highly advantageous over the prior art.